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1 | ------------------------------------------------------------------------------ |
2 | -- -- | |
3 | -- GNAT COMPILER COMPONENTS -- | |
4 | -- -- | |
5 | -- G N A T . D Y N A M I C _ T A B L E S -- | |
6 | -- -- | |
7 | -- S p e c -- | |
8 | -- -- | |
fbf5a39b | 9 | -- Copyright (C) 2000-2003 Ada Core Technologies, Inc. -- |
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10 | -- -- |
11 | -- GNAT is free software; you can redistribute it and/or modify it under -- | |
12 | -- terms of the GNU General Public License as published by the Free Soft- -- | |
13 | -- ware Foundation; either version 2, or (at your option) any later ver- -- | |
14 | -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- | |
15 | -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- | |
16 | -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- | |
17 | -- for more details. You should have received a copy of the GNU General -- | |
18 | -- Public License distributed with GNAT; see file COPYING. If not, write -- | |
19 | -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- | |
20 | -- MA 02111-1307, USA. -- | |
21 | -- -- | |
22 | -- As a special exception, if other files instantiate generics from this -- | |
23 | -- unit, or you link this unit with other files to produce an executable, -- | |
24 | -- this unit does not by itself cause the resulting executable to be -- | |
25 | -- covered by the GNU General Public License. This exception does not -- | |
26 | -- however invalidate any other reasons why the executable file might be -- | |
27 | -- covered by the GNU Public License. -- | |
28 | -- -- | |
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29 | -- GNAT was originally developed by the GNAT team at New York University. -- |
30 | -- Extensive contributions were provided by Ada Core Technologies Inc. -- | |
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31 | -- -- |
32 | ------------------------------------------------------------------------------ | |
33 | ||
34 | -- Resizable one dimensional array support | |
35 | ||
36 | -- This package provides an implementation of dynamically resizable one | |
37 | -- dimensional arrays. The idea is to mimic the normal Ada semantics for | |
38 | -- arrays as closely as possible with the one additional capability of | |
39 | -- dynamically modifying the value of the Last attribute. | |
40 | ||
41 | -- This package provides a facility similar to that of GNAT.Table, except | |
42 | -- that this package declares a type that can be used to define dynamic | |
43 | -- instances of the table, while an instantiation of GNAT.Table creates a | |
44 | -- single instance of the table type. | |
45 | ||
46 | -- Note that this interface should remain synchronized with those in | |
47 | -- GNAT.Table and the GNAT compiler source unit Table to keep as much | |
48 | -- coherency as possible between these three related units. | |
49 | ||
50 | generic | |
51 | type Table_Component_Type is private; | |
52 | type Table_Index_Type is range <>; | |
53 | ||
54 | Table_Low_Bound : Table_Index_Type; | |
55 | Table_Initial : Positive; | |
56 | Table_Increment : Natural; | |
57 | ||
58 | package GNAT.Dynamic_Tables is | |
59 | ||
60 | -- Table_Component_Type and Table_Index_Type specify the type of the | |
61 | -- array, Table_Low_Bound is the lower bound. Index_type must be an | |
62 | -- integer type. The effect is roughly to declare: | |
63 | ||
64 | -- Table : array (Table_Low_Bound .. <>) of Table_Component_Type; | |
65 | ||
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66 | -- Note: since the upper bound can be one less than the lower |
67 | -- bound for an empty array, the table index type must be able | |
68 | -- to cover this range, e.g. if the lower bound is 1, then the | |
69 | -- Table_Index_Type should be Natural rather than Positive. | |
70 | ||
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71 | -- Table_Component_Type may be any Ada type, except that controlled |
72 | -- types are not supported. Note however that default initialization | |
73 | -- will NOT occur for array components. | |
74 | ||
75 | -- The Table_Initial values controls the allocation of the table when | |
76 | -- it is first allocated, either by default, or by an explicit Init | |
77 | -- call. | |
78 | ||
79 | -- The Table_Increment value controls the amount of increase, if the | |
80 | -- table has to be increased in size. The value given is a percentage | |
81 | -- value (e.g. 100 = increase table size by 100%, i.e. double it). | |
82 | ||
83 | -- The Last and Set_Last subprograms provide control over the current | |
84 | -- logical allocation. They are quite efficient, so they can be used | |
85 | -- freely (expensive reallocation occurs only at major granularity | |
86 | -- chunks controlled by the allocation parameters). | |
87 | ||
88 | -- Note: we do not make the table components aliased, since this would | |
89 | -- restrict the use of table for discriminated types. If it is necessary | |
90 | -- to take the access of a table element, use Unrestricted_Access. | |
91 | ||
92 | type Table_Type is | |
93 | array (Table_Index_Type range <>) of Table_Component_Type; | |
94 | ||
95 | subtype Big_Table_Type is | |
96 | Table_Type (Table_Low_Bound .. Table_Index_Type'Last); | |
97 | -- We work with pointers to a bogus array type that is constrained | |
98 | -- with the maximum possible range bound. This means that the pointer | |
99 | -- is a thin pointer, which is more efficient. Since subscript checks | |
100 | -- in any case must be on the logical, rather than physical bounds, | |
101 | -- safety is not compromised by this approach. | |
102 | ||
103 | type Table_Ptr is access all Big_Table_Type; | |
104 | -- The table is actually represented as a pointer to allow | |
105 | -- reallocation. | |
106 | ||
107 | type Table_Private is private; | |
108 | -- table private data that is not exported in Instance. | |
109 | ||
110 | type Instance is record | |
111 | Table : aliased Table_Ptr := null; | |
112 | -- The table itself. The lower bound is the value of Low_Bound. | |
113 | -- Logically the upper bound is the current value of Last (although | |
114 | -- the actual size of the allocated table may be larger than this). | |
115 | -- The program may only access and modify Table entries in the | |
116 | -- range First .. Last. | |
117 | ||
118 | P : Table_Private; | |
119 | end record; | |
120 | ||
121 | procedure Init (T : in out Instance); | |
122 | -- This procedure allocates a new table of size Initial (freeing any | |
123 | -- previously allocated larger table). Init must be called before using | |
124 | -- the table. Init is convenient in reestablishing a table for new use. | |
125 | ||
126 | function Last (T : in Instance) return Table_Index_Type; | |
127 | pragma Inline (Last); | |
128 | -- Returns the current value of the last used entry in the table, | |
129 | -- which can then be used as a subscript for Table. Note that the | |
130 | -- only way to modify Last is to call the Set_Last procedure. Last | |
131 | -- must always be used to determine the logically last entry. | |
132 | ||
133 | procedure Release (T : in out Instance); | |
134 | -- Storage is allocated in chunks according to the values given in the | |
135 | -- Initial and Increment parameters. A call to Release releases all | |
136 | -- storage that is allocated, but is not logically part of the current | |
137 | -- array value. Current array values are not affected by this call. | |
138 | ||
139 | procedure Free (T : in out Instance); | |
140 | -- Free all allocated memory for the table. A call to init is required | |
141 | -- before any use of this table after calling Free. | |
142 | ||
143 | First : constant Table_Index_Type := Table_Low_Bound; | |
144 | -- Export First as synonym for Low_Bound (parallel with use of Last) | |
145 | ||
146 | procedure Set_Last (T : in out Instance; New_Val : Table_Index_Type); | |
147 | pragma Inline (Set_Last); | |
148 | -- This procedure sets Last to the indicated value. If necessary the | |
638e383e | 149 | -- table is reallocated to accommodate the new value (i.e. on return |
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150 | -- the allocated table has an upper bound of at least Last). If |
151 | -- Set_Last reduces the size of the table, then logically entries are | |
152 | -- removed from the table. If Set_Last increases the size of the | |
153 | -- table, then new entries are logically added to the table. | |
154 | ||
155 | procedure Increment_Last (T : in out Instance); | |
156 | pragma Inline (Increment_Last); | |
fbf5a39b | 157 | -- Adds 1 to Last (same as Set_Last (Last + 1) |
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158 | |
159 | procedure Decrement_Last (T : in out Instance); | |
160 | pragma Inline (Decrement_Last); | |
fbf5a39b | 161 | -- Subtracts 1 from Last (same as Set_Last (Last - 1) |
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162 | |
163 | procedure Append (T : in out Instance; New_Val : Table_Component_Type); | |
164 | pragma Inline (Append); | |
165 | -- Equivalent to: | |
166 | -- Increment_Last (T); | |
167 | -- T.Table (T.Last) := New_Val; | |
168 | -- i.e. the table size is increased by one, and the given new item | |
169 | -- stored in the newly created table element. | |
170 | ||
171 | procedure Set_Item | |
172 | (T : in out Instance; | |
173 | Index : Table_Index_Type; | |
174 | Item : Table_Component_Type); | |
175 | pragma Inline (Set_Item); | |
176 | -- Put Item in the table at position Index. The table is expanded if | |
177 | -- current table length is less than Index and in that case Last is set to | |
178 | -- Index. Item will replace any value already present in the table at this | |
179 | -- position. | |
180 | ||
181 | procedure Allocate (T : in out Instance; Num : Integer := 1); | |
182 | pragma Inline (Allocate); | |
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183 | -- Adds Num to Last |
184 | ||
185 | generic | |
186 | with procedure Action | |
187 | (Index : Table_Index_Type; | |
188 | Item : Table_Component_Type; | |
189 | Quit : in out Boolean) is <>; | |
190 | procedure For_Each (Table : Instance); | |
191 | -- Calls procedure Action for each component of the table Table, or until | |
192 | -- one of these calls set Quit to True. | |
193 | ||
194 | generic | |
195 | with function Lt (Comp1, Comp2 : Table_Component_Type) return Boolean; | |
196 | procedure Sort_Table (Table : in out Instance); | |
197 | -- This procedure sorts the components of table Table into ascending | |
198 | -- order making calls to Lt to do required comparisons, and using | |
199 | -- assignments to move components around. The Lt function returns True | |
200 | -- if Comp1 is less than Comp2 (in the sense of the desired sort), and | |
201 | -- False if Comp1 is greater than Comp2. For equal objects it does not | |
202 | -- matter if True or False is returned (it is slightly more efficient | |
203 | -- to return False). The sort is not stable (the order of equal items | |
204 | -- in the table is not preserved). | |
205 | ||
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206 | |
207 | private | |
208 | ||
209 | type Table_Private is record | |
210 | Max : Integer; | |
211 | -- Subscript of the maximum entry in the currently allocated table | |
212 | ||
213 | Length : Integer := 0; | |
214 | -- Number of entries in currently allocated table. The value of zero | |
215 | -- ensures that we initially allocate the table. | |
216 | ||
217 | Last_Val : Integer; | |
218 | -- Current value of Last. | |
219 | end record; | |
220 | ||
221 | end GNAT.Dynamic_Tables; |